Andreev reflection at the altermagnet-superconductor interface

TL;DR

This paper investigates Andreev reflection at altermagnet-superconductor interfaces, revealing orientation-dependent behaviors and potential for advanced superconducting heterostructures like Josephson π junctions.

Contribution

It introduces the study of Andreev reflection in altermagnets, highlighting their unique properties and differences from other magnetic materials in superconducting interfaces.

Findings

Orientation affects Andreev reflection behavior.

Resonant states depend on tunneling barrier strength.

Sensitivity to disorder varies with surface orientation.

Abstract

Altermagnets are a new class of magnetic materials, which exhibit large spin splitting, but due to the combined spin and real space group symmetry protection maintain zero net macroscopic magnetization. Such a characteristic may prove them to be superior in applications in superconducting heterostructures and thus here we investigate the Andreev reflection at the altermagnet/superconductor interface. We compare and contrast altermagnets to other magnetic materials, revealing qualitative differences in the behavior of altermagnetic junction depending on the Fermi surface orientation. We study the resonant states arising in setups with strong tunneling barriers and show that sensitivity to non-magnetic disorder is also dependent on the orientation. Our results provide a building block for altermagnetic superconducting heterostructures such as Josephson $\pi$ junctions with superior properties.